Montepuez ruby deposit, Mozambique - Gemfields (LON:GEM)

The Montepuez ruby deposit is located in the northeast of Mozambique in the Cabo Delgado province. Covering approximately 33,600 hectares, it is the most significant recently discovered ruby deposit in the world. Precious stones miner Gemfields confirmed its Montepuez ruby mine in Mozambique has enough reserves to last at least 20 years.

Estimates of probable ore reserves are 432 million carats at a diluted grade of 15.7 carats per tonne over 21 years.

Less than 10 years after discoveries near Montepuez in 2009, rubies from Mozambique have taken a major place in the trade. Gemfields held its first rough ruby auction in June 2014. In 2016, mining for gemstones or gold without a license became a crime punishable by three years in jail. In 2017 the government targeted buyers. Police operations were launched and many foreign buyers were arrested, fined, and expelled. Gemfields later had its most successful ruby auction ever in June 2017, recording more than US$54 million in sales.

The concession is located at a geologically critical junction between the north-south trending Mozambique Belt and the east-west trending Zambezi Belt. Primary rubies are formed when fluid derived from the parental magma interacted with the host rocks under a silica unsaturated environment. After hundreds of millions years of erosion, rubies are liberated from the host rock and transported and concentrated by water and eventually settled in alluvial, colluvial, and eluvial deposits.

In November 2016 Gemfields discovered a 40.23-carat ruby at Montepuez which it has called “one of the most important rubies unearthed in recent times” While the yield from the rough depends on a number of factors, including the shape, inclusions, and the nature of the crystal. With a yield of 30 percent to 40 percent one should get a 12 to 16 carat gem.

The important question would be how clean the stone is and whether or not it requires heat treatment. A clean stone without heat treatment is far more valuable. If this is the case, the piece of rough could yield a cut and polished ruby with a wholesale value of $1.5 million or more. The stone is significant because it attests to the mine’s ability to produce important rubies. Due to the rarity of rubies, the discovery of a 40-carat ruby is comparable to finding a 100-carat rough diamond.

Gems of the Smithsonian

The Bismarck Sapphire Necklace is a sapphire necklace designed by Cartier in 1935. It is named after Countess Mona von Bismarck, who donated the piece to the Smithsonian in 1967. The 98.6 carat table cut Bismarck Sapphire is mounted in a pendant surrounded by baguette-cut diamonds.

The Dom Pedro Aquamarine

The Carmen Lúcia Ruby is a 23.1-carat Burmese ruby set in a platinum ring with diamonds. It was donated by Peter Buck in memory of his wife Carmen Lúcia. The stone was mined from the Mogok region of Burma in the 1930s.

The Blue Heart Diamond was found at the Premier Mine, South Africa in 1908. This 30.62 carat heart-shaped, brilliant cut blue diamond was faceted in 1910 from a 100.5 carat piece of rough.

The DeYoung Red Diamond is one of the largest known natural fancy dark red diamonds. It is a modified round brilliant cut VS-2 diamond of 5.03 carats. The diamond was acquired by S. Sydney DeYoung, a Boston jeweler, as part of a collection of estate jewelry and identified, incorrectly, as a garnet. It was gifted to the National Gem Collection in 1987.

The Chalk Emerald is a 37.8-carat emerald designed by Harry Winston. It is surrounded by 60 pear-shaped diamonds totaling 15 carats. It was donated to the Smithsonian by Mr. and Mrs. O. Roy Chalk in 1972

Pink pear shape diamond weighing 2.90 carats.

The Hooker Emerald is 75.47 carats. It was once the property of Abdul Hamid II, Sultan of the Ottoman Empire (1876-1909) who wore it in his belt buckle. Tiffany & Co. purchased the emerald at auction in 1911. The stone originated from Colombia and was probably shipped to Europe by Spanish conquistadores in the 16th or 17th century. Mrs. Janet Annenberg Hooker donated it to the Smithsonian 1977.

The 58.19-carat Maharani Cat’s Eye from Sri Lanka. Chrysoberyl. The optical phenomenon of chatoyancy is caused by the reflection of light off inclusions of fine, needle-like crystals, usually rutile.

The Victoria-Transvaal Diamond was cut from a 240-carat rough stone found at the Premier Mine in Transvaal, South Africa, in 1951. The diamond is 67.89 carats, is a pear-shaped brilliant cut, and has 116 facets.

Hope Diamond

Heart-shaped brooch has a 96-carat amethyst surrounded by diamonds.

The Hall Sapphire Necklace, designed by Harry Winston, Inc., features 36 cushion-cut sapphires from Sri Lanka, totaling 195 carats, set in platinum accented by 435 pear-shaped and round brilliant-cut diamonds, totaling 83.75 carats.

These two large, pear-shaped diamonds weigh 14.25 and 20.34 carats respectively are set in earrings that belonged to Marie Antoinette, the Queen of France who was guillotined in 1793 during the French Revolution.

The Petersen Tanzanite Brooch. Pair of matched tanzanite gems about 30 carats. The brooch was designed by Harry Winston in 1991 and has 24 carats of diamonds. The tanzanite “flowers” can be detached and worn as earrings. The Petersen Tanzanite Brooch was gifted to the National Gem Collection in 2002. The Sherman Diamond is one of five pendants from a diamond necklace. The necklace was a gift from the khedive of Egypt to Civil War General William Sherman for his daughter’s wedding in 1874. The necklace was divided among his three daughters. The pendant has an 8.52-carat pear shaped diamond surrounded by 17 round diamonds.

http://geogallery.si.edu/index.php/en/gems/all/mineral/any/

Top Gems at Auction in 2014

11. An 89.23-carat Pear-Shaped Diamond – $11,085,000 10. A 70.33-carat Cushion Brilliant-Cut Diamond – $14,201,234

9. A 75.97-carat Pear-Shaped D Colour, Flawless Diamond – $14,474,732 8. Pair of Fancy Vivid Blue & Fancy Vivid Pink Diamond Earrings, by Bvlgari – $15,820,731

7. The Graff Fancy Vivid Yellow diamond weighs 100.09 carats and is graded VS2 clarity. It set a new world auction record for a yellow diamond.– $16,347,848 6. The Blue Belle of Asia – $17,295,796. At 392.52 carats, the Ceylon sapphire is the fourth largest faceted sapphire in history and set a new world auction record for any sapphire.

A Belle Époque Diamond Devant-de-Corsage Brooch, by Cartier – $17,581,612

An 8.41-carat Fancy Vivid Purple-Pink Diamond – $17,778,247

3. The Winston Blue – $23,795,372

The Hutton-Mdivani Jadeite Necklace – $27,441,026. The Hutton-Mdivani Necklace set a new world auction record for any jadeite jewelry and a new world auction record for a Cartier jewel. The Zoe Diamond – $32,645,000 ($3,348,205 per carat) The Zoe diamond set a new world auction record for any blue diamond and a new world auction record for price-per-carat for any diamond.

WD Lab Grown Diamonds grows 9.04-carat round brilliant diamond

WD Lab Grown Diamonds announced it successfully grew a 9.04-carat round brilliant diamond using the company's patented Chemical Vapor Deposition (CVD) process. The diamond, which was completed in March was graded as I color VS2 clarity IDEAL cut and stands as the world's largest known CVD diamond. The company broke its own CVD diamond size record that was previously announced in January – increasing its record-breaking feat from 6 carats to more than 9 carats.

Fura Gems finds giant emerald at Coscuez mine in Colombia

Fura Gems (TSX-V:FUR), has found a 25.97-carat rough emerald at its Coscuez emerald mine in Colombia. The company says the gemstone is a “rare and exceptional” one, given its size, colour saturation and clarity. It has been named the “ÄRE Emerald”, after a figure in ancient Colombian mythology responsible for the creation of emeralds in the country’s Boyacá region: the Fura and Tena mountains, as well as the Rio Minero River.

Paraiba Tourmaline

Tourmaline is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and comes in a wide variety of colours. Almost every colour of tourmaline can be found in Brazil, especially in the Brazilian states of Minas Gerais and Bahia. In 1989, miners discovered a unique and brightly colored variety of tourmaline in the state of Paraíba.

The new type of tourmaline, known as paraiba tourmaline, came in blue and green. Brazilian paraiba tourmaline usually contains abundant inclusions. It was found the element copper was important in the coloration of the stone. These cupriferous tourmalines are small, rare and precious. Their turquoise to green colours are not duplicated in any other gemstone in the world.

Another highly valuable variety is chrome tourmaline, a rare type of dravite tourmaline from Tanzania. Chrome tourmaline is a rich green colour due to the presence of chromium atoms in the crystal; chromium also produces the green colour of emeralds.